MGladiator83

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So, the debate, at least for me, is settled

I watched all the videos. Scrubbed all the forums. Checked all the pricing too.

Like a lot of us, My JTR rides on 37 mud terrains on a mopar lift. For everyone who says the 4.10s are fine with this kind of set up, you are right. You can get down the road just fine, no surging, reasonable power. Its also true that doing so comes with a lot of gear hunting on the highway. But its seriously not an issue, you’ll just spDend a lot of time in 6th going down the road.

But, as decent as the 4.10s are with allowing you to get down the road, the 4.88’s are a game changer, and its not even close.

Elite Offroad here in Birmingham did a great job dropping in some Dana Spicer 4.88 gears and master install kit on my JTR this week. We used a Superchips Flashcal to dial it in. This thing will never be a hellcat in terms of pep but it moved itself with way more ease with the new rings. Very peppy, and more importantly, super smooth at part throttle. The jeep also uses all its gears and settles in to 8th without bogging. It shows off the strengths of this 8 speed well, up hill downshifts arehandled crisply and the engine never lags or bogs.

All of us have different driving styles. But for me, on the highway running 70 on flat ground i could achieve 20mpg running 2100 rpms. Pic below confirms what I saw.

We’ll put it on a trail after the break in period but I am expecting greater control off road and also less need for 4 lo on average trails here in the southeast. Hope these notes help any who are trying to make a decision. Zero regrets here, its really a no brainer and highly recommend.

D6500408-81E6-477F-B1BC-216A43660D87.jpeg
I support this as another owner who has installed 4.88’s



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Keller

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What do you need for install other than the gear sets (F/R) and tools?
 

No IFS

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There is no debate, its 5.13 for me. 4.88 not enough gear for 37” But thats why they make different ratios for different people. I’m very happy.
 

LostWoods

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What do you need for install other than the gear sets (F/R) and tools?
Bearings and a shim kit. With a press you can reuse bearings but IMO it's just a good idea to do fresh ones that don't have previous wear. The only special tool you should need is a beam torque wrench so you can properly set pinion preload if you don't have a feel for it.
 

J.Noack

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There is no debate, its 5.13 for me. 4.88 not enough gear for 37” But thats why they make different ratios for different people. I’m very happy.
I’m on 40’s so went with 5.13’s as well. Also doing RCV shafts to be on the safe side. Went ahead and replaced both driveshafts due to the lift. So it’s looking like my transfer case will be the victim in all of this lol.
We will see how it turns out concerning performance.
 

Alabama Mud Machine

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Bearings and a shim kit. With a press you can reuse bearings but IMO it's just a good idea to do fresh ones that don't have previous wear. The only special tool you should need is a beam torque wrench so you can properly set pinion preload if you don't have a feel for it.
You will also need a precise dial indicator with a magnetic base to set backlash.
 
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PyrPatriot

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I'm getting around 18 mixed with 35s on stock max tow 4.10 gears. I understand everyone wants to feel good about the gear change but 4.10 to 4.88 is not a very big jump. If you have 3.73 then yes a bigger change. I would go 5.13 or 5.38 without hesitation if you have a larger than 35" tire.
Same. 4.10 on heavy 35s (Falken MTs) and went from 20mpg factory, to 18-19mpg on 32" Falkens, and now 17-18 on the 35s. I stay in 8th gear on the highway as much as I did with the 32" Falkens.

5.13s should give you the performance needed up to 40" tires off road. Now, I'd like more explanation on the physical size of the gears and possible failure. 4.10 is larger physically than 5.13, so much so that the 5.13s are just not as strong?


3-6-jkgearing-jpg.jpg
 

LostWoods

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Same. 4.10 on heavy 35s (Falken MTs) and went from 20mpg factory, to 18-19mpg on 32" Falkens, and now 17-18 on the 35s. I stay in 8th gear on the highway as much as I did with the 32" Falkens.

5.13s should give you the performance needed up to 40" tires off road. Now, I'd like more explanation on the physical size of the gears and possible failure. 4.10 is larger physically than 5.13, so much so that the 5.13s are just not as strong?


3-6-jkgearing-jpg.jpg
This was designed for the JK's 6AT so you actually get more leeway out of it with the new ZF box. 4.88s on a JK will give you lower final ratio (higher numerically; i.e. higher RPM at any given speed) than 5.13s on the JL/JT.

If it weren't for the lower pinion tooth count vs 4.88s, I'd say 5.13s are a no-brainer even with 35's if you plan on wheeling regularly.
 

PyrPatriot

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This was designed for the JK's 6AT so you actually get more leeway out of it with the new ZF box. 4.88s on a JK will give you lower final ratio (higher numerically; i.e. higher RPM at any given speed) than 5.13s on the JL/JT.

If it weren't for the lower pinion tooth count vs 4.88s, I'd say 5.13s are a no-brainer even with 35's if you plan on wheeling regularly.
Oh ok
 

Nate

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Revolution 4.88s and 37s here. Perfect combination.
 

                           













































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